President Trump stepped away from the precipice of an immediate military conflict with Iran on Friday, calling off a strike in response to Iran’s downing of a U.S. surveillance drone.

But with the United States and Iran still locked in an adversarial pose, with none of their underlying grievances resolved, the prospect for fresh brinkmanship loomed as U.S. officials contemplated an alternative response.

Key Trump allies on Capitol Hill said Friday that they expected the president to order a “non-kinetic” measure, suggesting economic sanctions or some other nonmilitary punishment for Iran’s destroying the aircraft.

Meanwhile, Iran has accused the United States of committing “economic terrorism” by imposing rounds of sanctions that are strangling its economy — raising the prospects of more attacks on oil tankers or U.S. assets in the region.

The precariousness of the moment was compounded by widespread uncertainty about the president’s decision-making process, which he detailed Friday in tweets and statements that drew scrutiny from even his own aides.

Early in the day, the president said he called off the attack at the last minute because it would have killed 150 people in retaliation for the downing of the drone. “We were cocked & loaded to retaliate last night on 3 different sights when I asked, how many will die,” he tweeted.

But administration officials said Trump was told earlier Thursday how many casualties could occur if a strike on Iran were carried out and that he had given the green light that morning to prepare the operation.

The confusion reinforced concerns about the Trump administration’s credibility at a time of military crisis.

The decision has divided his top advisers, with senior Pentagon officials opposing the decision to strike and national security adviser John Bolton strongly supporting it.

Iran said Friday that the United States had “no justification” for a retaliatory strike and vowed to respond “firmly” to any U.S. military action.

Trump’s morning tweets appeared to gloss over the fact that he was the one, as commander in chief, who had ordered the retaliation against Iran in the first place.

Trump administration officials, who like others spoke on the condition of anonymity to discuss sensitive national security decisions, said the president approved the strikes after Iran’s Islamic Revolutionary Guard Corps shot down the Navy RQ-4 Global Hawk on Thursday.

But he later changed his mind, the officials said.

An U.S. Air Force photo, released June 20, 2019, shows a RQ-4 Global Hawk unmanned surveillance aircraft, the type of craft that Iran shot down Thursday. (U.S. Air Force/AFP/Getty Images)

A senior U.S. defense official said Friday morning that the Pentagon had Navy assets poised to strike Iran if directed, including ships accompanying the aircraft carrier USS Abraham Lincoln. Those attacks could have included airstrikes with jets or — more likely — Tomahawk cruise missiles, the official said.

Trump’s initial tweets suggested that he had canceled his own order. “10 minutes before the strike I stopped it,” he said. But in an interview with NBC’s Chuck Todd for “Meet the Press,” the president said that he had not given final approval for any strikes and that no planes were in the air.

“Nothing was greenlighted until the very end because things change,” Trump said in the interview.

In his Twitter posts Friday morning, Trump wrote that “sanctions are biting & more added last night.” However, the Treasury Department did not add any sanctions against Iran on Thursday night.

There was also confusion about whether the United States and Iran were communicating at a time when they have very few diplomatic contacts.

The Federal Aviation Administration late Thursday barred U.S.-registered commercial aircraft from operating over the Persian Gulf and the Gulf of Oman because of an increase in military activities and political tensions that it said might “place commercial flights at risk.”

Several U.S. and international carriers said that they had canceled flights through Iranian airspace or were taking steps to avoid the Strait of Hormuz.

The day’s events have left lawmakers in both parties confused about whether an imminent crisis was averted.

House Speaker Nancy Pelosi (D-Calif.) said Friday that she was not informed in advance of Trump’s plans to strike Iran but described the latest events as a “dangerous, high-tension situation.”

Senate Majority Leader Mitch McConnell (R-Ky.) expressed confidence in the president, but several hawks in Congress said the only appropriate response would be a swift military counterstrike against Iran.

“They’re trying to break our will and intimidate us to come to the negotiating table,” Sen. Lindsey O. Graham (R-S.C.) said of the Iranians.

Senate Foreign Relations Committee Chairman James E. Risch (R-Idaho), said Trump would probably choose from the options laid out before lawmakers in a Situation Room meeting Thursday. “There’s going to be something more proportional, obviously, and I suspect it’s going to be not kinetic action,” Risch said Friday.

Trump’s comments Thursday also left room for questions about how his administration planned to respond to Iran. Immediately after the drone’s downing, he tweeted that “Iran made a very big mistake.”

But Trump said he found it “hard to believe” that the attack on the drone “was intentional” on the part of Iran’s top officials. He also noted that the aircraft was unmanned. “There was no man or woman in it,” he said. “It would have made a big difference” if a plane carrying people had been shot down. “It would have made a big, big difference.”

The commander of the Revolutionary Guard’s aerospace division said Friday that Iran had sent “warnings” to the drone before shooting it down. In an interview with Iran’s state-controlled broadcaster, Brig. Gen. Amir Ali Hajizadeh said a final warning was sent at 3:55 a.m. local time Thursday.

“When it did not redirect its route and continued flying toward and into our territory, we had to shoot it at 4:05 a.m.,” he said. “Our national security is a red line.”

He said Iran refrained from also shooting down a U.S. P-8 Poseidon patrol aircraft with 35 people on board that he asserted had accompanied the drone into Iranian airspace. His claim could not immediately be verified.

The destruction of the drone followed a number of recent incidents, including attacks on tankers, that American officials have depicted as part of an Iranian effort to hurt the United States and its allies in the region. The United States has continued its “maximum pressure” campaign against Iran, which the Trump administration has identified as its main adversary in the Middle East.

Tehran has responded with defiance to the campaign, which was launched after Trump withdrew the United States from the 2015 Iran nuclear deal and has included designating the Revolutionary Guard as a terrorist group and taking steps to cut off Iranian oil sales.

Saudi Arabia’s deputy defense minister said Friday on Twitter that he met in Riyadh with Brian Hook, the State Department’s special representative for Iran, “to explore the latest efforts to counter hostile Iranian acts.”

Hook called Friday for measures to “de-escalate” the tension with Iran. “Our diplomacy does not give Iran the right to respond with military force; Iran needs to meet our diplomacy with diplomacy and not military force,” Reuters quoted Hook as saying at a news conference in the Saudi capital. “It’s important we do everything we can to de-escalate.”

In this photo released on May 11, 2014, by the office of Iran’s supreme leader, a Third of Khordad air defense system is displayed while the leader, Ayatollah Ali Khamenei, right, visits an exhibition of the Revolutionary Guard's aerospace division. (Office of the Iranian Supreme Leader/AP)